Side Burner Flame Inside the Casing

Newly acquired weber genesis from the late 80's, with side burner. The side burner will start and you can feel heat, but there is no visible flame coming from the burner. I opened the case and found that the flame is burning inside the casing- there is an opening in the tube (i think to let oxygen in) and fire is coming out of that. Anyone know how to fix?

Your burner tube is clogged possibly with insect nests